Technical Field
The present disclosure relates to an organic light-emitting diode (OLED) display apparatus and a method of manufacturing the same. More specifically, the present disclosure relates to an OLED display apparatus with improved repairability.
Description of the Related Art
An organic light-emitting diode (OLED) display apparatus has a high luminance and a low operating voltage. In addition, since an OLED display apparatus is a self luminance display apparatus, it has a high contrast ratio and can be made as an ultra-thin display apparatus. Moreover, it has a short response time of several microseconds (μs) and thus, can easily present moving pictures, has little limitation on viewing angle, and can be operated stably even at a low temperature. Further, an OLED display apparatus is driven with a low voltage from DC 5 V to 15 V, and thus, it is easy to design and fabricate a driving circuit.
With such advantages, OLED display apparatuses are recently employed by a variety of IT devices such as TVs, monitors, mobile phones.
A more detailed description of a basic structure of an OLED display apparatus will be given below.
An OLED display apparatus includes an array element and an organic light-emitting element disposed on a substrate. The array element includes a driving element for controlling display data that is connected to a gate line and a data line, and at least one driving thin-film transistor connected to an organic light-emitting element. The organic light-emitting element includes a first electrode connected to the driving thin-film transistor, an organic emission layer, and a second electrode.
The OLED display apparatus as described above may include organic emission layers which are made of luminous materials emitting red, green and blue, respectively, to represent a full color. Alternatively, the OLED display apparatus may include an organic emission layer which is made of an organic luminous material emitting light of white, and color filter patterns containing red, green and blue pigments for pixel regions, respectively, such that the light of white from the organic emission layer passes through the color filter patterns, to represent a full color.
Such an OLED display apparatus may suffer failures arising where the performance of a thin-film transistor may deteriorate or a short-circuit may be formed therein during a process of fabricating lines or switching thin-film transistors and driving thin-film transistors.
If a thin-film transistor formed in a pixel region fails to normally operate, no current or voltage is applied to an organic light-emitting element connected to the thin-film transistor, such that the pixel region becomes a dark spot. On the other hand, if a short-circuit is formed between the source electrode and the drain electrode of the thin-film transistor, the thin-film transistor fails to normally operate such that a voltage applied to the source electrode is not turned on/off but is directly applied to the drain electrode. When this happens, the pixel region remains in an on-state and thus becomes a bright spot.
Once a pixel region becomes a dark spot, it may be very difficult to repair it in the state-of-the-art. If a pixel region becomes a bright spot, there is a way to conceal it by laser cutting the electrical connection between the driving thin-film transistor and the first electrode and the electrical connection to the driving thin-film transistor or a driving element for controlling display data, thereby making the bright spot into a dark spot.
A bright spot can be easily perceived by viewers and thus, degrades display quality. Accordingly, even with a single bright spot, the display apparatus may be regarded as a defective product. On the other hand, a dark spot is rarely perceived by viewers, and thus, ten to twenty dark spots can be typically ignored at the time of releasing a display apparatus. For this reason, a bright spot can be concealed by making it into a dark spot.
However, during a process of repairing using a laser, a planarization layer or a thin-film transistor protective layer made of an organic material may be damaged by a thermal energy created by a laser irradiation, and thus, an outgas containing oxygen or hydrogen may be generated. Such an outgas may react with an organic emission layer or an electrode connected to the organic emission layer of the organic light-emitting element, and more dark spots may be created over time. As a result, the display quality of the OLED display apparatus may be degraded.
As another defects can be created during the process of repairing a bright spot into a dark spot, the cost of repair may be significantly increased, which would result in increased manufacturing costs.